1. Field of the Invention
This invention pertains generally to shotguns, and more particularly to improving the accuracy of shorter length shotgun barrels, reducing felt recoil, and providing for interchangeability of shot pellets and slugs in a single barrel.
2. Description of the Background Art
Conventional shotguns employ barrels of various configurations. Most notable are variations in chokes to change the pattern of the shot pellets. Barrel lengths vary also, since the amount of recoil which is felt by the user decreases as the barrel length is increased. Accuracy is also improved by using longer barrels.
A shotgun, however, is generally a short range weapon. As smaller shot is used, a smaller effective range results. The tighter the shot pattern, the more accurate the shotgun is at longer ranges. The size of the pattern is a function of several variables which include the degree of choke if any, the size of the shot, and the load.
Various attempts at improving shotgun barrels, reducing recoil, and increasing accuracy have been made over the years. For example, French 912,871 discloses a modified choke. Italian 462,064 discloses an over/under barrel where one barrel contains a choke. British 854,516 discloses a barrel configuration for a recoilless rifle in which the barrel contains multiple tapers to serve as a seat for the cartridge case, as well as to create a smaller diameter chamber for the projectile. British 9,208 discloses a rifled shotgun barrel having an expanded chamber near the muzzle end. British 9,164 discloses a rifled barrel of similar configuration to that shown in British 9,208. British 4,294 discloses a barrel having two conically shaped sections in which the inside of the barrel tapers and then flares toward the muzzle end. French 364,168 discloses a shotgun barrel having a tapered section on the muzzle side of the forcing cone. French 468,883 discloses a shotgun barrel having a constricted forcing cone and a larger diameter barrel.
U.S. Pat. No. 2,323,306 issued to Campbell on Jul. 6, 1943, discloses a saluting tube for blank shot shells which includes both tapered and flared portions. The purpose of this configuration is to increase the pressure build up in the barrel and to make more noise upon firing. U.S. Pat. No. 2,742,821 issued to Sweetman on Apr. 24, 1956, discloses a venting technique for a tapered bore gun. The tapered bore is used with a deformable projectile. The vents relieve pressure on the cartridge case to prevent mutilation. U.S. Pat. No. 1,858,560 issued to Rosenstiel on May 17, 1932, discloses a shotgun barrel in which the inner diameter toward the muzzle end is less than the breach end, and then flares out at the muzzle. This modification serves retard the wads and explosive gasses to prevent them from interfering with the passage of the shot. U.S. Pat. No. 14,597 issued to Buckel & Dorsch on Apr. 8, 1856, discloses a shotgun barrel having an undulating inner diameter. U.S. Pat. No. 4,071,971 issued to Tornas on Feb. 7, 1978, discloses a shotgun barrel having grooved rifling near the muzzle end, with the inner diameter of the barrel tapering and then flaring in the area of the grooved rifling. U.S. Pat. No. 157,008 issued to Kerr on Nov. 17, 1874, discloses a gun barrel with an enlarged bore covering approximately one-third of the overall barrel length, the enlargement occurring near the muzzle end. U.S. Pat. No. 863,431 issued to Parker on Aug. 13, 1907, discloses a barrel which tapers from the chamber toward the muzzle, the angle of the taper changing radically in the area of the muzzle, and then flaring out again near the muzzle opening. U.S. Pat. No. 2,054,132 issued to Lewis on Sep. 15, 1936, discloses a shotgun barrel having two sections which taper in opposite directions. U.S. Pat. No. 618,901 issued to Peterson on Feb. 7, 1899, discloses a shotgun barrel which is ported near the muzzle end.
The foregoing approaches, however, are directed to standard length barrels and hunting or target applications. In a combat situation, police officers and federal agents often require a short barrelled weapon that can be easily handled or concealed. Barrel lengths of approximately 48 cm or less are often referred to as "riot" shotguns and provide much greater firepower than a pistol. However, as the distance to the target increases, the shot become more dispersed and accuracy suffers. Also, because a shorter barrel weighs less, there is less weight to cushion the recoil which results from the high power of a shot shell load. In addition, in order to change from using a load containing shot pellets to a load containing solid slugs in a combat situation, it is often necessary to change barrels in order to maintain accuracy due to the differing characteristics of the loads.
Therefore, there is a need for a short barrel for combat and law enforcement use that achieves a high degree of accuracy with low recoil characteristics, as well as provides for interchangeability between shot shell loads and solid slugs. The present invention satisfies those needs.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.